Torque disconnect mechanism with brake interlock

Abstract

A vehicle transmission has first and second shafts rotatable in a housing, a spring applied, pressure released brake mechanism for preventing vehicle movement, and a torque disconnect mechanism for controlling transmission of torque from the first shaft to the second shaft. An interlock mechanism includes an opening formed in the housing through which an operator may access the torque disconnect mechanism, a fluid pressure supply passage for communicating pressurized fluid to the brake mechanism, a dump port formed in the housing in a wall of the opening, a pressure dump passage communicating the supply passage with the dump port, and a plug member mountable in the opening. The plug member closes the dump port and closes communication between the dump passage and the environment when the plug member is mounted in the opening The dump port and the dump passage are communicated with the environment, and the brake is spring applied when the plug member is removed from the opening.

I claim:  
     
       1. In a vehicle transmission having first and second shafts rotatable in a housing, a spring applied, pressure released brake mechanism for preventing vehicle movement and a torque disconnect mechanism for controlling transmission of torque from the first shaft to the second shaft, an interlock mechanism comprising: 
       an opening formed in the housing through which an operator may access the torque disconnect mechanism;  
       a fluid pressure supply passage for communicating pressurized fluid to the brake mechanism;  
       a dump port formed in the housing in a wall of the opening;  
       a pressure dump passage communicating the supply passage with the dump port; and  
       a plug member mountable in the opening, the plug member closing the dump port and closing communication between the dump passage and the environment when the plug member is mounted in the opening, and the dump port and the dump passage being communicated with the environment when the plug member is removed from the opening.  
     
     
       2. The interlock mechanism of  claim 1 , wherein: 
       the fluid pressure supply passage and the pressure dump passage are formed in the housing.  
     
     
       3. A power transmission comprising: 
       first and second shafts rotatable in a housing;  
       a torque disconnect mechanism for controlling transmission of torque from the first shaft to the second shaft;  
       an opening formed in the housing through which an operator may access the torque disconnect mechanism;  
       a plug member removably mountable in the opening;  
       a brake mechanism engagable to prevent rotation of the second shaft; and  
       an interlock mechanism operatively interconnecting the plug member and the brake mechanism, the interlock mechanism operating to cause the brake mechanism to engage when the plug member is removed from the opening.  
     
     
       4. The power transmission of  claim 3 , wherein: 
       the brake mechanism comprises a spring applied, pressure released brake communicated with a source of brake pressure via a supply passage; and  
       the interlock mechanism comprises a dump port formed in the housing in a wall of the opening, a pressure dump passage communicating the supply passage with the dump port, the plug member closing the dump port and closing communication between the dump passage and the environment when the plug member is mounted in the opening, and the dump port and the dump passage being communicated with the environment when the plug member is removed from the opening.  
     
     
       5. The interlock mechanism of  claim 4 , wherein: 
       the supply passage and the pressure dump passage are formed in the housing.